One of the important parameters influencing durability or wear resistance of devices employing a lubricating composition is the effectiveness of phosphorus antiwear or extreme pressure additives at providing devices with appropriate protection under various conditions of load and speed. However, many of the phosphorus antiwear or extreme pressure additives contain sulphur. Due to increasing environmental concerns, the presence of sulphur in antiwear or extreme pressure additives is becoming less desirable. In, addition, many of the sulphur-containing antiwear or extreme pressure additives evolve volatile sulphur species, resulting in lubricating compositions containing antiwear or extreme pressure additives having an odour, which may also be detrimental to the environment or evolve emissions that may be higher than increasingly tighter health and safety legislation specifies.
In addition, many of the antiwear or extreme pressure additives employed have at least one of (i) limited extreme pressure and antiwear performance over a wide range of operating conditions, (ii) limited oxidative stability, (iii) form deposits, or (iv) cause corrosion (for example copper corrosion).
Driveline power transmitting devices (such as gears or transmissions, especially axle fluids and manual transmission fluids (MTFs)), and grease applications, present highly challenging technological problems and solutions for satisfying the multiple and often conflicting lubricating requirements, whilst providing durability and cleanliness.
U.S. Pat. No. 3,197,405 discloses lubricating oils containing amine salts of phosphorylated hydroxy-substituted triesters of phosphorothioic acids. The amine salts of the phosphorylated hydroxy-substituted triesters of phosphorothioic acids are useful in lubricating compositions to provide antiwear performance in gear oils, internal combustion engines and automotive transmissions.
U.S. Pat. Nos. 6,730,640; 6,872,693; 6,656,887; and US Patent Applications 2005/0143266; 2005/0130855; 2005/0107269; all disclose at least one of (i) divalent metal salt of a thiophosphoric acid esters, (ii) divalent metal salt of a phosphoric acid ester, or (iii) mixtures thereof of (i) and (ii).
Consequently, it would be desirable to provide an antiwear agent and balanced lubricant composition to meet the needs of driveline power transmitting devices or grease applications without the disadvantages of known lubricating compositions. The present invention provides such an antiwear agent and lubricating compositions thereof.